Speaker
Description
The dominance of dark energy in the universe has necessitated ways to introduce a repulsive gravity source to make $q$ negative. The models for the dark energy range from $\Lambda$-CDM, K-essence, Chaplygin gas, etc. We look at the possibility where the interaction parameter $\Gamma$ plays a vital role in various cosmological models, particularly those involving interactions between dark energy and other cosmic components, such as matter (including baryonic and dark matter) and radiation. It quantifies the strength of the interaction between dark energy and these components. In that case, understanding how $\Gamma$ changes over time is crucial for precisely modeling the behavior of dark energy in the universe. In response to this paradigm, we propose an alternative framework for studying dark energy and its role in structure formation in the early universe. And assume that the interaction between dark energy and matter is a simple linear coupling with a varying equation of state. This allows us to track the rate of interaction, the entropy of dark energy and matter, and their densities over conformal time. To explore this framework, we investigate three different models: time-varying $\Lambda$, Generalized Chaplygin gas, and K-essence models. Each model has a different value of $\Gamma$. Our results suggest that while considering interactions between dark energy and matter, the Generalized Chaplygin gas model, when coupled with an interaction term, could provide a better fit to the observed power spectrum, particularly at $ell<70$ when $\Gamma$ falls within a specific range. This result is significant in two ways: 1) The standard $\Lambda$-CDM model doesn't fit well to explain the uncertainties arising in this specific range. 2) This behavior of Generalized Chaplygin gas is a new insight for constraining observational data or ruling out other models. For instance, if we measure a very small value of $\Gamma$, it would rule out the K-essence model, as it is highly sensitive to the value of $\Gamma$. Conversely, if $\Gamma$ is measured as non-zero, it would not rule out the K-essence model, as the Chaplygin gas model and the time-varying $\Lambda$ model are also sensitive to the value of $\Gamma$. The corresponding calculations show that the K-essence model ($\Gamma = 0.1 \pm 1 \%$) is more sensitive to the interaction between dark energy and matter due to its non-canonical kinetic term. On the other hand, the Chaplygin gas model ($\Gamma = 1.02 \pm 5 \%$) and the time-varying $\Lambda$ model ($\Gamma = 0.01 \pm 5 \%$) are canonical scalar field models. As a result, these models are less sensitive to the interaction between dark energy and matter compared to the K-essence model. Furthermore, the interaction parameter also acts to suppress the power spectrum at low-ell values, where the $\Lambda$-CDM model typically falls short in predicting observations. However, it is important to note that further investigation is necessary to refine constraints on model parameters and distinguish between different dark energy models. Since observational data on $\Gamma$ is currently weak, future observations are necessary to constrain its value and compare the predictions of the interacting dark energy model to observed data.
| pradosh.keshav@res.christuniversity.in | |
| Affiliation | Christ University |
